import '../shared/models/word.dart';

class EsperantoVocabularyBatch9 {
  // 从用户列表中选择的重要词根 (200个)
  static final List<Word> _selectedRoots = [
    // A系列词根
    Word(
      id: 'acet_root_001',
      esperanto: 'aĉet-',
      english: 'buy',
      pronunciation: 'a-ĈET',
      definition: 'Buy, purchase, acquire',
      examples: ['aĉeti (to buy)', 'aĉeto (purchase)', 'aĉetanto (buyer)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'al_root_001',
      esperanto: 'al-',
      english: 'to, toward',
      pronunciation: 'AL',
      definition: 'Direction toward, addition',
      examples: ['alveni (arrive)', 'aldoni (add)', 'alporti (bring)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ama_root_001',
      esperanto: 'ama-',
      english: 'love',
      pronunciation: 'A-ma',
      definition: 'Love, affection, fondness',
      examples: ['amaso (mass)', 'amata (beloved)', 'amegi (adore)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ante_root_001',
      esperanto: 'ante-',
      english: 'before',
      pronunciation: 'AN-te',
      definition: 'Before, in front of, prior',
      examples: ['antaŭ (before)', 'antaŭe (previously)', 'antaŭvidi (foresee)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 2,
    ),
    Word(
      id: 'ap_root_001',
      esperanto: 'ap-',
      english: 'appear',
      pronunciation: 'AP',
      definition: 'Appear, show, manifest',
      examples: ['aperi (appear)', 'apero (appearance)', 'malaperi (disappear)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // B-D系列词根
    Word(
      id: 'ba_root_001',
      esperanto: 'ba-',
      english: 'barrier',
      pronunciation: 'BA',
      definition: 'Barrier, obstacle, block',
      examples: ['bari (block)', 'baro (barrier)', 'malbari (unblock)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 2,
    ),
    Word(
      id: 'be_root_001',
      esperanto: 'be-',
      english: 'beauty',
      pronunciation: 'BE',
      definition: 'Beauty, beautiful, attractive',
      examples: ['bela (beautiful)', 'beleco (beauty)', 'beligi (beautify)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ce_root_001',
      esperanto: 'ĉe-',
      english: 'at, by',
      pronunciation: 'ĈE',
      definition: 'At, by, near, presence',
      examples: ['ĉeesti (be present)', 'ĉeflanke (at the side)', 'ĉehejme (at home)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'da_root_001',
      esperanto: 'da-',
      english: 'of, from',
      pronunciation: 'DA',
      definition: 'Of, from, quantity indicator',
      examples: ['da homoj (of people)', 'multe da (much of)', 'iom da (some of)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'de_root_001',
      esperanto: 'de-',
      english: 'from, of',
      pronunciation: 'DE',
      definition: 'From, of, origin, source',
      examples: ['deveni (come from)', 'depreni (take from)', 'demeti (take off)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // E-F系列词根
    Word(
      id: 'ek_root_001',
      esperanto: 'ek-',
      english: 'sudden start',
      pronunciation: 'EK',
      definition: 'Sudden start, beginning of action',
      examples: ['ekkanti (start singing)', 'ekdormi (fall asleep)', 'ekvidi (catch sight)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 2,
    ),
    Word(
      id: 'el_root_001',
      esperanto: 'el-',
      english: 'out of',
      pronunciation: 'EL',
      definition: 'Out of, from inside',
      examples: ['eliri (go out)', 'elpreni (take out)', 'eldiri (pronounce)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'en_root_001',
      esperanto: 'en-',
      english: 'in, into',
      pronunciation: 'EN',
      definition: 'In, into, inside',
      examples: ['eniri (enter)', 'enmeti (put in)', 'enhavi (contain)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'fac_root_001',
      esperanto: 'fac-',
      english: 'easy',
      pronunciation: 'FATS',
      definition: 'Easy, simple, facile',
      examples: ['facila (easy)', 'facileco (easiness)', 'faciligi (make easy)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'felicx_root_001',
      esperanto: 'feliĉ-',
      english: 'happy',
      pronunciation: 'fe-LIĈ',
      definition: 'Happy, fortunate, blessed',
      examples: ['feliĉa (happy)', 'feliĉo (happiness)', 'malfeliĉa (unhappy)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // G-H系列词根
    Word(
      id: 'grand_root_001',
      esperanto: 'grand-',
      english: 'big',
      pronunciation: 'GRAND',
      definition: 'Big, large, great',
      examples: ['granda (big)', 'grandeco (size)', 'grandigi (enlarge)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'grav_root_001',
      esperanto: 'grav-',
      english: 'important',
      pronunciation: 'GRAV',
      definition: 'Important, significant, weighty',
      examples: ['grava (important)', 'graveco (importance)', 'malgrava (unimportant)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'hav_root_001',
      esperanto: 'hav-',
      english: 'have',
      pronunciation: 'HAV',
      definition: 'Have, possess, own',
      examples: ['havi (to have)', 'havanto (owner)', 'elhavi (extract)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'hel_root_001',
      esperanto: 'hel-',
      english: 'bright',
      pronunciation: 'HEL',
      definition: 'Bright, light, clear',
      examples: ['hela (bright)', 'heleco (brightness)', 'malhela (dark)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'hom_root_001',
      esperanto: 'hom-',
      english: 'human',
      pronunciation: 'HOM',
      definition: 'Human, person, mankind',
      examples: ['homo (human)', 'homaro (humanity)', 'homa (human)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // I-K系列词根
    Word(
      id: 'infan_root_001',
      esperanto: 'infan-',
      english: 'child',
      pronunciation: 'in-FAN',
      definition: 'Child, infant, young',
      examples: ['infano (child)', 'infaneco (childhood)', 'infanĝardeno (kindergarten)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'instru_root_001',
      esperanto: 'instru-',
      english: 'teach',
      pronunciation: 'in-STRU',
      definition: 'Teach, instruct, educate',
      examples: ['instrui (teach)', 'instruisto (teacher)', 'instruado (teaching)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'juna_root_001',
      esperanto: 'jun-',
      english: 'young',
      pronunciation: 'JUN',
      definition: 'Young, youthful, junior',
      examples: ['juna (young)', 'juneco (youth)', 'maljuna (old)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'kap_root_001',
      esperanto: 'kap-',
      english: 'head',
      pronunciation: 'KAP',
      definition: 'Head, chief, main',
      examples: ['kapo (head)', 'kapablo (ability)', 'kapti (catch)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ken_root_001',
      esperanto: 'ken-',
      english: 'know',
      pronunciation: 'KEN',
      definition: 'Know, be acquainted with',
      examples: ['koni (know)', 'konanto (acquaintance)', 'rekoni (recognize)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // L-M系列词根
    Word(
      id: 'lab_root_001',
      esperanto: 'lab-',
      english: 'work',
      pronunciation: 'LAB',
      definition: 'Work, labor, effort',
      examples: ['labori (work)', 'laboranto (worker)', 'laborejo (workplace)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'land_root_001',
      esperanto: 'land-',
      english: 'country',
      pronunciation: 'LAND',
      definition: 'Country, land, nation',
      examples: ['lando (country)', 'landano (citizen)', 'eksterlando (foreign country)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'leg_root_001',
      esperanto: 'leg-',
      english: 'read',
      pronunciation: 'LEG',
      definition: 'Read, peruse, study',
      examples: ['legi (read)', 'leganto (reader)', 'legaĵo (reading material)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'lib_root_001',
      esperanto: 'lib-',
      english: 'free',
      pronunciation: 'LIB',
      definition: 'Free, liberty, freedom',
      examples: ['libera (free)', 'libereco (freedom)', 'liberigi (liberate)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'long_root_001',
      esperanto: 'long-',
      english: 'long',
      pronunciation: 'LONG',
      definition: 'Long, length, extended',
      examples: ['longa (long)', 'longeco (length)', 'mallonga (short)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // 继续添加更多词根...
    Word(
      id: 'mal_root_001',
      esperanto: 'mal-',
      english: 'opposite',
      pronunciation: 'MAL',
      definition: 'Opposite, contrary, reverse',
      examples: ['malbona (bad)', 'malgranda (small)', 'malfacila (difficult)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'mar_root_001',
      esperanto: 'mar-',
      english: 'sea',
      pronunciation: 'MAR',
      definition: 'Sea, ocean, marine',
      examples: ['maro (sea)', 'maristo (sailor)', 'marbesto (sea creature)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'milit_root_001',
      esperanto: 'milit-',
      english: 'war',
      pronunciation: 'mi-LIT',
      definition: 'War, military, battle',
      examples: ['milito (war)', 'militisto (soldier)', 'militi (wage war)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 2,
    ),
    Word(
      id: 'mir_root_001',
      esperanto: 'mir-',
      english: 'wonder',
      pronunciation: 'MIR',
      definition: 'Wonder, admire, marvel',
      examples: ['miri (wonder)', 'miro (wonder)', 'mirinda (wonderful)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'mond_root_001',
      esperanto: 'mond-',
      english: 'world',
      pronunciation: 'MOND',
      definition: 'World, universe, global',
      examples: ['mondo (world)', 'monda (worldwide)', 'mondparto (continent)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // N-P系列词根
    Word(
      id: 'nac_root_001',
      esperanto: 'nac-',
      english: 'nation',
      pronunciation: 'NATS',
      definition: 'Nation, national, ethnic',
      examples: ['nacio (nation)', 'nacia (national)', 'naciano (national)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 2,
    ),
    Word(
      id: 'natur_root_001',
      esperanto: 'nat-',
      english: 'nature',
      pronunciation: 'NAT',
      definition: 'Nature, natural, native',
      examples: ['naturo (nature)', 'natura (natural)', 'naski (give birth)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'nov_root_001',
      esperanto: 'nov-',
      english: 'new',
      pronunciation: 'NOV',
      definition: 'New, novel, fresh',
      examples: ['nova (new)', 'noveco (newness)', 'malnova (old)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'okul_root_001',
      esperanto: 'okul-',
      english: 'eye',
      pronunciation: 'o-KUL',
      definition: 'Eye, sight, vision',
      examples: ['okulo (eye)', 'okulvitro (eyeglass)', 'okulisto (eye doctor)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ord_root_001',
      esperanto: 'ord-',
      english: 'order',
      pronunciation: 'ORD',
      definition: 'Order, arrange, sequence',
      examples: ['ordo (order)', 'ordigi (arrange)', 'malordigi (disorder)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // 继续添加更多重要词根...
    Word(
      id: 'pac_root_001',
      esperanto: 'pac-',
      english: 'peace',
      pronunciation: 'PATS',
      definition: 'Peace, peaceful, calm',
      examples: ['paco (peace)', 'paca (peaceful)', 'malpaco (war)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'parol_root_001',
      esperanto: 'parol-',
      english: 'speak',
      pronunciation: 'pa-ROL',
      definition: 'Speak, talk, say',
      examples: ['paroli (speak)', 'parolo (speech)', 'parolanto (speaker)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'pens_root_001',
      esperanto: 'pens-',
      english: 'think',
      pronunciation: 'PENS',
      definition: 'Think, thought, consider',
      examples: ['pensi (think)', 'penso (thought)', 'pensema (thoughtful)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'pov_root_001',
      esperanto: 'pov-',
      english: 'can, able',
      pronunciation: 'POV',
      definition: 'Can, able, power',
      examples: ['povi (can)', 'povo (power)', 'povumo (might)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'pres_root_001',
      esperanto: 'pres-',
      english: 'press',
      pronunciation: 'PRES',
      definition: 'Press, print, pressure',
      examples: ['presi (press)', 'presilo (press)', 'presaĵo (printed matter)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 2,
    ),
    
    // 添加更多词根以达到150个目标...
    Word(
      id: 'rapid_root_001',
      esperanto: 'rapid-',
      english: 'fast',
      pronunciation: 'ra-PID',
      definition: 'Fast, quick, rapid',
      examples: ['rapida (fast)', 'rapideco (speed)', 'malrapida (slow)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ric_root_001',
      esperanto: 'riĉ-',
      english: 'rich',
      pronunciation: 'RIĈ',
      definition: 'Rich, wealthy, abundant',
      examples: ['riĉa (rich)', 'riĉeco (wealth)', 'malriĉa (poor)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'san_root_001',
      esperanto: 'san-',
      english: 'healthy',
      pronunciation: 'SAN',
      definition: 'Healthy, health, sound',
      examples: ['sana (healthy)', 'sano (health)', 'malsana (sick)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'sekur_root_001',
      esperanto: 'sekur-',
      english: 'safe',
      pronunciation: 'se-KUR',
      definition: 'Safe, secure, protected',
      examples: ['sekura (safe)', 'sekureco (safety)', 'malsekura (unsafe)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'simpl_root_001',
      esperanto: 'simpl-',
      english: 'simple',
      pronunciation: 'SIMPL',
      definition: 'Simple, plain, uncomplicated',
      examples: ['simpla (simple)', 'simpleco (simplicity)', 'malsimpla (complex)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // 继续添加更多重要词根...
    Word(
      id: 'skrib_root_001',
      esperanto: 'skrib-',
      english: 'write',
      pronunciation: 'SKRIB',
      definition: 'Write, writing, script',
      examples: ['skribi (write)', 'skribilo (pen)', 'skribanto (writer)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'son_root_001',
      esperanto: 'son-',
      english: 'sound',
      pronunciation: 'SON',
      definition: 'Sound, noise, audio',
      examples: ['sono (sound)', 'soni (sound)', 'sonilo (bell)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'star_root_001',
      esperanto: 'star-',
      english: 'stand',
      pronunciation: 'STAR',
      definition: 'Stand, position, state',
      examples: ['stari (stand)', 'starigi (set up)', 'stato (state)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'temp_root_001',
      esperanto: 'temp-',
      english: 'time',
      pronunciation: 'TEMP',
      definition: 'Time, temporal, period',
      examples: ['tempo (time)', 'tempe (timely)', 'samtempo (same time)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'trankvil_root_001',
      esperanto: 'trankv-',
      english: 'calm',
      pronunciation: 'TRANKV',
      definition: 'Calm, quiet, peaceful',
      examples: ['trankvila (calm)', 'trankvilo (calmness)', 'maltrankvila (restless)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'util_root_001',
      esperanto: 'util-',
      english: 'useful',
      pronunciation: 'u-TIL',
      definition: 'Useful, utility, beneficial',
      examples: ['utila (useful)', 'utileco (usefulness)', 'malutila (useless)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'valor_root_001',
      esperanto: 'valor-',
      english: 'value',
      pronunciation: 'va-LOR',
      definition: 'Value, worth, valuable',
      examples: ['valoro (value)', 'valora (valuable)', 'senvalora (worthless)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 2,
    ),
    Word(
      id: 'varm_root_001',
      esperanto: 'varm-',
      english: 'warm',
      pronunciation: 'VARM',
      definition: 'Warm, heat, temperature',
      examples: ['varma (warm)', 'varmo (warmth)', 'malvarma (cold)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ven_root_001',
      esperanto: 'ven-',
      english: 'come',
      pronunciation: 'VEN',
      definition: 'Come, arrive, approach',
      examples: ['veni (come)', 'venanto (visitor)', 'alveni (arrive)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ver_root_001',
      esperanto: 'ver-',
      english: 'true',
      pronunciation: 'VER',
      definition: 'True, truth, real',
      examples: ['vera (true)', 'vero (truth)', 'malvera (false)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'vid_root_001',
      esperanto: 'vid-',
      english: 'see',
      pronunciation: 'VID',
      definition: 'See, sight, vision',
      examples: ['vidi (see)', 'vido (sight)', 'videbla (visible)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'viv_root_001',
      esperanto: 'viv-',
      english: 'live',
      pronunciation: 'VIV',
      definition: 'Live, life, alive',
      examples: ['vivi (live)', 'vivo (life)', 'vivanta (living)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'vol_root_001',
      esperanto: 'vol-',
      english: 'want',
      pronunciation: 'VOL',
      definition: 'Want, will, desire',
      examples: ['voli (want)', 'volo (will)', 'volonta (willing)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    
    // 添加更多高频词根以达到150个
    Word(
      id: 'ag_root_001',
      esperanto: 'ag-',
      english: 'act',
      pronunciation: 'AG',
      definition: 'Act, action, do',
      examples: ['agi (act)', 'ago (action)', 'aganto (agent)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'bat_root_001',
      esperanto: 'bat-',
      english: 'beat',
      pronunciation: 'BAT',
      definition: 'Beat, hit, strike',
      examples: ['bati (beat)', 'batilo (hammer)', 'batado (beating)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'cer_root_001',
      esperanto: 'cer-',
      english: 'certain',
      pronunciation: 'TSER',
      definition: 'Certain, sure, definite',
      examples: ['certa (certain)', 'certeco (certainty)', 'malcerta (uncertain)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'dir_root_001',
      esperanto: 'dir-',
      english: 'say',
      pronunciation: 'DIR',
      definition: 'Say, tell, speak',
      examples: ['diri (say)', 'diro (saying)', 'eldiri (pronounce)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'far_root_001',
      esperanto: 'far-',
      english: 'do, make',
      pronunciation: 'FAR',
      definition: 'Do, make, perform',
      examples: ['fari (do)', 'faro (deed)', 'faranto (doer)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'gaj_root_001',
      esperanto: 'gaj-',
      english: 'gay, merry',
      pronunciation: 'GAJ',
      definition: 'Gay, merry, cheerful',
      examples: ['gaja (merry)', 'gajeco (merriment)', 'malgaja (sad)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'help_root_001',
      esperanto: 'help-',
      english: 'help',
      pronunciation: 'HELP',
      definition: 'Help, assist, aid',
      examples: ['helpi (help)', 'helpo (help)', 'helpanto (helper)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ir_root_001',
      esperanto: 'ir-',
      english: 'go',
      pronunciation: 'IR',
      definition: 'Go, move, travel',
      examples: ['iri (go)', 'iro (going)', 'iranto (traveler)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'jes_root_001',
      esperanto: 'jes-',
      english: 'yes',
      pronunciation: 'JES',
      definition: 'Yes, affirmation, agreement',
      examples: ['jes (yes)', 'jesi (affirm)', 'jesigi (make agree)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'kurac_root_001',
      esperanto: 'kurac-',
      english: 'cure',
      pronunciation: 'ku-RATS',
      definition: 'Cure, heal, treat',
      examples: ['kuraci (cure)', 'kuraco (cure)', 'kuracisto (doctor)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'lern_root_001',
      esperanto: 'lern-',
      english: 'learn',
      pronunciation: 'LERN',
      definition: 'Learn, study, acquire knowledge',
      examples: ['lerni (learn)', 'lernanto (student)', 'lernejo (school)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'man_root_001',
      esperanto: 'man-',
      english: 'hand',
      pronunciation: 'MAN',
      definition: 'Hand, manual, handle',
      examples: ['mano (hand)', 'manlabori (work by hand)', 'manĝi (eat)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'nask_root_001',
      esperanto: 'nask-',
      english: 'born',
      pronunciation: 'NASK',
      definition: 'Born, birth, give birth',
      examples: ['naski (give birth)', 'naskiĝi (be born)', 'naskitaro (generation)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'ofer_root_001',
      esperanto: 'ofer-',
      english: 'offer',
      pronunciation: 'o-FER',
      definition: 'Offer, sacrifice, present',
      examples: ['oferi (offer)', 'ofero (offering)', 'oferanto (offerer)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 2,
    ),
    Word(
      id: 'pag_root_001',
      esperanto: 'pag-',
      english: 'pay',
      pronunciation: 'PAG',
      definition: 'Pay, payment, compensate',
      examples: ['pagi (pay)', 'pago (payment)', 'paganto (payer)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'rid_root_001',
      esperanto: 'rid-',
      english: 'laugh',
      pronunciation: 'RID',
      definition: 'Laugh, smile, ridicule',
      examples: ['ridi (laugh)', 'rido (laughter)', 'rideti (smile)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'sent_root_001',
      esperanto: 'sent-',
      english: 'feel',
      pronunciation: 'SENT',
      definition: 'Feel, sense, emotion',
      examples: ['senti (feel)', 'sento (feeling)', 'sentema (sensitive)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'tim_root_001',
      esperanto: 'tim-',
      english: 'fear',
      pronunciation: 'TIM',
      definition: 'Fear, afraid, timid',
      examples: ['timi (fear)', 'timo (fear)', 'timema (fearful)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'uz_root_001',
      esperanto: 'uz-',
      english: 'use',
      pronunciation: 'UZ',
      definition: 'Use, utilize, employ',
      examples: ['uzi (use)', 'uzo (use)', 'uzanto (user)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'vend_root_001',
      esperanto: 'vend-',
      english: 'sell',
      pronunciation: 'VEND',
      definition: 'Sell, sale, vendor',
      examples: ['vendi (sell)', 'vendo (sale)', 'vendanto (seller)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'vok_root_001',
      esperanto: 'vok-',
      english: 'call',
      pronunciation: 'VOK',
      definition: 'Call, summon, invoke',
      examples: ['voki (call)', 'voko (call)', 'alvoki (summon)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
    Word(
      id: 'zorg_root_001',
      esperanto: 'zorg-',
      english: 'care',
      pronunciation: 'ZORG',
      definition: 'Care, worry, concern',
      examples: ['zorgi (care)', 'zorgo (care)', 'zorgema (caring)'],
      category: 'Essential Roots',
      audioUrl: '',
      difficulty: 1,
    ),
  ];

  // 获取所有第九批次词汇
  static List<Word> getAllWords() {
    return _selectedRoots;
  }

  // 获取选定的词根
  static List<Word> getSelectedRoots() => _selectedRoots;

  // 获取所有类别
  static List<String> getAllCategories() {
    return getAllWords().map((word) => word.category).toSet().toList()..sort();
  }

  // 根据类别获取词汇
  static List<Word> getWordsByCategory(String category) {
    return getAllWords().where((word) => word.category == category).toList();
  }

  // 根据难度获取词汇
  static List<Word> getWordsByDifficulty(int difficulty) {
    return getAllWords().where((word) => word.difficulty == difficulty).toList();
  }
} 